This invention relates to an afterburner for a wood stove and particularly to an afterburner which can comprise a retrofit assembly for attachment to existing wood stoves in position between the flue outlet of the wood stove and the conventional flue of the wood stove.
Catalytic combusters or afterburners have become available recently for use with wood stoves to burn the gases issuing from the burning wood which gases normally escape from the wood stove in the flue. This has a number of advantages. Firstly the burning of the combustible gases can be used to provide additional heat thus substantially increasing the efficiency of combustion of the wood fuel. Secondly and in some areas more importantly, the burning of the combustible gases very much reduces the amount of pollution issued from the wood stove thus allowing the wood stove to be used in areas where otherwise only smokeless fuel is allowed to be burned.
Designs have been developed for using the combusters in wood stoves and one particular problem which must be taken into account is that the combuster only operates when the gases reach a particular temperature and therefore at start up of the combustion it is necessary to remove the combuster from the flue gases and return it to the flue gases when they reach the desired temperature. Various arrangements have been proposed for varying the path of the flue gases so that at start up they are diverted from the combuster. Normally this is done using a damper which opens a first path remote from the combuster to allow the flue gases to escape directly to the flue while closing the combuster and vice versa when the gases have reached the required temperature closing the diverting path and opening the path through the combuster.
None of the designs proposed has been entirely satisfactory and certainly no design has been proposed which is particularly suitable as a retrofit assembly to enable the afterburner to be sold separately from the wood stove for application to existing wood stoves already in the field.